net: export physical port id via sysfs

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: Narendra K <narendra_k@dell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/net-sysfs.c

@@ -334,6 +334,27 @@ static ssize_t store_group(struct device *dev, struct device_attribute *attr,
 	return netdev_store(dev, attr, buf, len, change_group);
 }
 
+static ssize_t show_phys_port_id(struct device *dev,
+				 struct device_attribute *attr, char *buf)
+{
+	struct net_device *netdev = to_net_dev(dev);
+	ssize_t ret = -EINVAL;
+
+	if (!rtnl_trylock())
+		return restart_syscall();
+
+	if (dev_isalive(netdev)) {
+		struct netdev_phys_port_id ppid;
+
+		ret = dev_get_phys_port_id(netdev, &ppid);
+		if (!ret)
+			ret = sprintf(buf, "%*phN\n", ppid.id_len, ppid.id);
+	}
+	rtnl_unlock();
+
+	return ret;
+}
+
 static struct device_attribute net_class_attributes[] = {
 	__ATTR(addr_assign_type, S_IRUGO, show_addr_assign_type, NULL),
 	__ATTR(addr_len, S_IRUGO, show_addr_len, NULL),
@@ -355,6 +376,7 @@ static struct device_attribute net_class_attributes[] = {
 	__ATTR(tx_queue_len, S_IRUGO | S_IWUSR, show_tx_queue_len,
 	       store_tx_queue_len),
 	__ATTR(netdev_group, S_IRUGO | S_IWUSR, show_group, store_group),
+	__ATTR(phys_port_id, S_IRUGO, show_phys_port_id, NULL),
 	{}
 };